- Introduced a new `ExtensionJobRegistry` to manage custom job types for extensions at runtime.
- Added `host_register_job` function to facilitate job registration from WASM extensions.
- Updated `PluginEnv` and `PluginManager` to include job registry functionality.
- Enhanced the `job` macro to support automatic job registration during plugin initialization.
- Updated documentation and tests to reflect the new job registration capabilities.
- Added `README_EXTENSIONS.md` to document the WASM extension system, outlining its features, quick start guide, and future plans.
- Implemented `WasmJob` for executing WASM extension jobs, including methods for job dispatching and state management.
- Enhanced `CoreContext` to include a `plugin_manager`, facilitating the management of extensions.
- Created integration tests for WASM job execution, ensuring the functionality of the new system.
- Removed the obsolete `sync_leadership` column from the database schema, streamlining the data model.
- Updated various modules to support the new extension architecture and improve overall system integration.
